A multichip module assembler oftentimes receives integrated circuit die that have already been tested by the die manufacturer to assure that the die work correctly. These die are typically tested as a completed integrated circuit package. To utilize a particular die with a multichip module a chemical etching process is often used to remove the material encapsulating the die until the wire-bond to the lead frame is exposed. The wire from the wire-bond is clipped at the die and the wire-bond ball is then stamped to provide reasonably uniform height. This process is known as stud bumping.
The stud bumps resulting from the stud bumping process may be troublesome to multichip assemblers because voids may result between the die and the polyimide flex circuit when the die is coupled thereto. This is a result of the non-planar surface associated with the stud bumps. This severely impairs yield.
Previous methods of removing the stud bumps have been inadequate. For example, mechanical removal techniques such as grinding may ruin the die or may not be adequate to cause the planar surface. Chemical removal techniques may also ruin the die by etching away too much material, which may lead to the removal of the contact pads. These processes are also expensive.